1. Field of the Invention
This invention relates to a method of and apparatus for severing a sheet of refractory material and, more particularly, to severing bulb edges of a sheet cut from a continuous glass ribbon.
2. Discussion of the Prior Art
As taught in U.S. Pat. No. 3,998,616 in the manufacture of a glass ribbon by the float method, a continuous ribbon of molten glass is controllably cooled as it moves through a forming chamber on a pool of molten metal. The edges of the molten glass as it cools are engaged by attenuating machines to move the edges relative to one another to provide a dimensionally stable glass ribbon having a thickness other than equilibrium thickness. The glass ribbon after sequentially exiting the forming chamber and annealing lehr is cut into sections normally called lehr ends. Because the edges of the lehr ends contacted by the attenuating machines, i.e., bulb edges are not usable they are removed.
In the prior art the bulb edges are removed by advancing the lehr end through a scoring station where a score is imposed adjacent each of the bulb edges and thereafter moving the scored lehr end into a snapping position. In the snapping position a rigid elongated member moves downward to sever each bulb edge from the lehr end. Although the above technique is acceptable for removing bulb edges from a stationary lehr end it would be advantageous to provide additional severing techniques that may be used to remove bulb edges from stationary or moving lehr ends.